Integration of biologging and non-invasive physiological assessment to uncover seasonal changes in reproduction and daily activity patterns in free-living subterranean rodents

TACHINARDI P; SILVA JS; ALVARENGA DE OLIVEIRA C; VALENTINUZZI VS; ODA GA

Amelia Island, Florida-Virtual

Congreso; SRBR- Society for Research in Biological Rhythms; 2020

SRBR Society

Background and objectives: The Anillaco tuco-tuco (Ctenomys aff. knighti) is a subterranean rodent from the semi-arid Northwest of Argentina. It is diurnal in nature but nocturnal in the laboratory. This flexibility in rhythmic patterns suggests an interaction of the circadian system with biotic and abiotic factors. Since many of these factors change seasonally in nature, it is proposed that rhythmic patterns also undergo seasonal changes, following physiological changes such as the ones in reproductive status. To understand the interplay between seasonal changes in tuco-tucos, physiology and daily activity patterns, we are measuring daily rhythms in free-living tuco-tucos throughout the year while also characterizing their seasonal reproductive cycle as well as assessing endocrine markers for stress and energetic statuses. Methods: Individuals are captured and assessed morphologically for reproductive status, receive a collar with activity- and light-loggers and have their faeces collected for the measurement of faecal metabolites of sex steroids, glucocorticoids and thyroid hormones. Individuals are then released in the field and recaptured after seven days to retrieve data from the loggers. Results: Most pregnant and lactating females found during spring and none during the winter, suggesting seasonality in reproduction. Diurnal patterns of activity and daily light exposure were displayed by most individuals during all seasons. Timing of daily activity onsets displayed a remarkable relationship to changes in sunrise time throughout the year. Differences in activity patterns between males and females were mostly seen during spring, when females displayed earlier onset of activity and higher levels of daily activity, which is probably related to their higher energetic demands due to reproductive status. Conclusions: Our preliminary results suggest that seasonal changes in rhythmic parameters can be related to reproductive status in females.